Silicone elastomeric attachment strip(s)

Abstract

Silicone elastomeric attachment strips useful in structural glazing applications and a two-part condensation curable silicone composition from which they are cured. More particularly, this disclosure relates to a silicone elastomeric attachment strip comprising a silicone elastomeric material that is designed to bond glazing units to structural elements in e.g., curtain wall applications, which strips do not contain a pressure sensitive adhesive. The silicone elastomeric attachment strips are prepared by curing the two-part condensation curable silicone composition which contains a silicone and titanium-based reaction product as a catalyst. A method of utilising same in said insulating glazing and curtain wall applications is also provided.

Description

[0001] SILICONE ELASTOMERIC ATTACHMENT STRIP(S) This disclosure relates to silicone elastomeric attachment strips useful in structural glazing applications and a two-part condensation curable silicone composition from which they are cured. More particularly, this disclosure relates to a silicone elastomeric attachment strip comprising a silicone elastomeric material that is designed to bond glazing units to structural elements in e.g., curtain wall applications, which strips do not contain a pressure sensitive adhesive. The silicone elastomeric attachment strips are prepared by curing the two-part condensation curable silicone composition which contains a silicone and titanium-based reaction product as a catalyst. A method of utilising same in said insulating glazing and curtain wall applications is also provided. Silicone structural glazing is a means of utilizing a silicone adhesive / sealant to attach glass, metal, or other panel materials to the structure of a building, e.g., to form a curtain wall façade which is an outer covering of a building designed to be non-structural i.e., it does not support the building as a whole, it merely supports its own weight. Curtain wall facades are designed to transfer incident horizontal wind loads (which can be extremely high based on the design, height, and location of the building) to the main building structure through connections at floors or columns of the building and are additionally designed to resist air and water infiltration. Curtain-wall façade assemblies are typically designed using lightweight support / frame materials, to reduce construction costs and minimise the weight of the facade. Hence, extruded aluminium members, or the like, are often used to form light weight frames / supports for a variety of glazing units, such as panels or infills, which may be inserted and fixed in place in / on said frames / supports. The glazing units i.e., panels or infills may be, for the sake of example, made from glass, stone veneer, metal, louvres, shadow boxes, and operable windows or vents. The glazing units e.g., panels or infills (hereafter referred to as panels) may contain a single pane of glass, laminated glass, double glazed insulating glass units (IGUs) or triple glazed IGUs. Wind load and other impact loads on the façade are transferred from the panel, through the structural silicone sealant to the structure of the building. Hence, a silicone sealant must maintain adhesive and cohesive integrity. Structural glazing (SG) is a high-performance application and not all silicone sealants are suitable for this application. Only structural glazing sealants which have been developed and tested specifically for structural glazing applications are used. Common to all of these systems is that structural silicone sealant is used to structurally attach glass or another material to the building structure using one of several systems such as 4-sided structural glazing systems where e.g., glass is supported on all four edges of the glass with structural silicone; 2-sided structural glazing systems where structural silicone is used on two of the four sides of the glass. The other two sides of the glass are either mechanically supported or are not structurally supported by a frame. Other forms such as slope glazing, where structural glazing is applied on a façade that is not vertical may also be utilised. Every structural glazing system requires a diligent and thorough procedure to ensure that the structural sealants are correctly applied involving for example, cleaning, priming and placing procedures. In order to ensure the correct amount of sealant is applied for the bond strength required between the substrate and e.g., a glazing unit and as such the glazing unit has to be correctly placed to ensure an appropriate structural glazing cavity is formed which is of the required dimensions e.g., a required distance apart to enable the structural glazing joint cavity to be completely filled with structural sealant to ensure the joint therebetween has an acceptable “structural bite”. Such processes may utilise adhesive tapes coated with pressure sensitive adhesives to position the glass panels correctly on a substrate and to maintain the substrate and the glazing unit the correct distance apart to form the desired cavity. Examples of such adhesive tapes comprising pressure sensitive adhesives are described in US8141324 and EP0728166. For the avoidance of doubt a pressure sensitive adhesive is a non-reactive adhesive which forms an adhesive bond with a substrate when pressure is applied, causing the adhesive to bond to a substrate surface. Typically, no solvent, water or heat etc. is required to “activate” the adhesion. The adhesive tapes may be, for the sake of example, a polyurethane foam support tape or closed-cell PVC foam support tape having, in each case, two sides of the support tape coated in a pressure sensitive adhesive. The adhesive tapes are designed to provide sufficient initial adhesion to the substrate and the glazing panel to maintain them a uniform distance apart, whilst forming the cavity with a combination with the edges of the substrate and glazing unit into which the structural silicone sealant is injected. Once the cavity has been completely filled with the structural silicone sealant, it is generally left to cure for up to several days. This system may suffer from drawbacks such as long times needed to cure the sealant before a prefabricated unit can be moved, a high mullion width as well as potentially inadequate thermal resistance, and sound damping from the exterior. US8141324B2 describes the use of a tape which comprises a silicone foam support bearing a pressure sensitive adhesive on opposing sides of the tape. There are also similar acrylic-based tapes with pressure sensitive adhesive on opposing sides of the tape. In both instances the pressure sensitive adhesives function as the means of adhesion between the tape and the substrate and the tape and the glazing unit. The tapes described above tend to have a relatively low strength, resulting in the need for large surface area amounts of tape between the substrate and the glazing panel. Such preformed tapes are generally considered to be difficult to handle for large glazing units having glass panes and are not considered easy to apply. This is because they may require a lot of manual steps to complete the adhesion process. Furthermore, acrylic based tapes have the added disadvantage of a limited resistance to UV exposure. Hence, there is a continuing need in industry to improve the performance such tapes or the like in e.g., structural glazing applications. There is provided herein a two-part silicone elastomeric attachment strip composition wherein: a first part composition comprises the following components: (a) a titanium-based reaction product obtained or obtainable from a process comprising the steps of: (i) mixing a first ingredient, an alkoxy titanium compound having from 2 to 4 alkoxy groups with a second ingredient, a linear or branched polydiorganosiloxane polymer having at least two terminal silanol groups per molecule; (ii) enabling the first and second ingredients to react together by stirring under vacuum to form a reaction product; and (iii) collecting the reaction product of step (ii); (b) at least one linear or branched polydiorganosiloxane polymer(s) having at least two terminal silanol groups per molecule; and a second part of the composition comprises the following components: (a’) at least one trimethoxy terminated polysiloxane(s) (b’) a bis(trialkoxysilyl)alkane having from 8 to 20 carbons per molecule, a trialkoxyphenylsilane having from 8 to 20 carbons per molecule; or a mixture thereof; and a component (c) which is mixed into the first part composition, the second part composition or both the first part composition and the second part composition; wherein: (c) is at least one filler, comprising fumed silica, precipitated silica, precipitated calcium carbonate or a mixture thereof, which filler is optionally hydrophobically treated; which composition has a molar ratio of Si-OH bonds : Si-alkoxy bonds of from 0.1 : 1 to 0.5 : 1. There is also provided a silicone elastomeric attachment strip which is the cured product of the above two-part silicone elastomeric attachment strip composition. Such silicone elastomeric attachment strips as described herein are, after cure, not sticky to the touch, unlike pressure sensitive adhesive materials. They chemically interact with primers pre-applied onto a target substrate surface. Hence the silicone elastomeric attachment strips once cured remain easy to handle until brought into contact with a pre- applied primer on a substrate surface. There is also provided a method of preparing a silicone elastomeric attachment strip comprising the steps of (A) preparing a first part composition by mixing components (a) and (b) where: (a) is a titanium-based reaction product obtained or obtainable from a process comprising the steps of: (i) mixing a first ingredient, an alkoxy titanium compound having from 2 to 4 alkoxy groups with a second ingredient, a linear or branched polydiorganosiloxane polymer having at least two terminal silanol groups per molecule; (ii) enabling the first and second ingredients to react together by stirring under vacuum to form a reaction product; and (iii) collecting the reaction product of step (ii); (b) at least one linear or branched polydiorganosiloxane polymer having at least two terminal silanol groups per molecule; (B) separately preparing a second part composition by mixing components (a’) and (b’) where: (a’) is at least one trimethoxy terminated polysiloxane; and (b’) is a bis(trialkoxysilyl)alkane having from 8 to 20 carbons per molecule, a trialkoxyphenylsilane having from 8 to 20 carbons per molecule; or a mixture thereof; and a component (c) which is mixed into the first part composition, the second part composition or both the first part composition and the second part composition; wherein: (c) is at least one filler, comprising fumed silica, precipitated silica, precipitated calcium carbonate or a mixture thereof, which filler is optionally hydrophobically treated; (C) Mixing the first part composition and the second part composition together in a suitable weight ratio to form a final silicone elastomeric attachment strip composition such that the final silicone elastomeric attachment strip composition has a molar ratio of Si-OH bonds : Si-alkoxy bonds of from 0.1 : 1 to 0.5 : 1; and either (D) or (E), wherein: (D) is introducing the final silicone elastomeric attachment strip composition into a suitable non-stick mold and curing to form a silicone elastomeric attachment strip; or (E) is applying the final silicone elastomeric attachment strip composition on to a previously primed substrate surface using a non-stick profile to mold a silicone elastomeric attachment strip on the substrate surface and curing said final silicone elastomeric attachment strip composition. There is also provided a silicone elastomeric attachment strip made in accordance with the above method. There is also provided a use of a silicone elastomeric attachment strip produced by the method described above to adhere a primed first substrate to a primed second substrate. There is also provided a curtain wall unit comprising: (I) a frame member, (II) a curtain wall panel, and (III) a silicone elastomeric attachment strip comprising the cured product of a two-part silicone elastomeric attachment strip composition wherein: a first part composition comprises the following components: (a) a titanium-based reaction product obtained or obtainable from a process comprising the steps of: (i) mixing a first ingredient, an alkoxy titanium compound having from 2 to 4 alkoxy groups with a second ingredient, a linear or branched polydiorganosiloxane polymer having at least two terminal silanol groups per molecule; (ii) enabling the first and second ingredients to react together by stirring under vacuum to form a reaction product; and (iii) collecting the reaction product of step (ii); (b) at least one linear or branched polydiorganosiloxane polymer(s) having at least two terminal silanol groups per molecule; and a second part of the composition comprises the following components: (a’) at least one trimethoxy terminated polysiloxane(s) (b’) a bis(trialkoxysilyl)alkane having from 8 to 20 carbons per molecule, a trialkoxyphenylsilane having from 8 to 20 carbons per molecule; or a mixture thereof; and a component (c) which is mixed into the first part composition, the second part composition or both the first part composition and the second part composition; wherein: (c) is at least one filler, comprising fumed silica, precipitated silica, precipitated calcium carbonate or a mixture thereof, which filler is optionally hydrophobically treated; which composition has a molar ratio of Si-OH bonds : Si-alkoxy bonds of from 0.1 : 1 to 0.5 : 1; and where the silicone elastomeric attachment strip is interposed between the frame member (I) and the curtain wall panel (II) and structurally attaches the curtain wall panel (II) to the frame member (I). The two-part silicone elastomeric attachment strip composition is not a pressure sensitive adhesive composition and as such when cured the silicone elastomeric attachment strip, does not adhere to a substrate when pressure is applied. It remains completely separate from the substrate when the pressure is released. Instead, once cured, whilst non-tacky to the touch it will undergo a chemical reaction with a pre-applied primer on the substrate surface when the two are placed in contact (without the need for more pressure than the pressure needed to wet the surface with the elastomer). The silicone elastomeric attachment strip does not require any form of support; it is substantially or completely made from the cured two-part silicone elastomeric attachment strip composition described herein. The two-part silicone elastomeric attachment strip composition may be applied on to an aluminum profile as a wet applied system and left to cure. Once cured, the aluminum profile is fully adhered to the resulting cured silicone elastomeric attachment strip and the opposite side of the strip is ready to be adhered to the glazing unit e.g., a glass pane once the glazing unit has been primed over a designated area. The silicone elastomeric attachment strip, once applied to the glazing unit glass, almost immediately generates an initial green strength of about 0.1 MPa. A few days later the silicone elastomeric attachment strip was found to develop an approximately 100% cohesive failure strength with a tensile strength greater than (>) 0.3 MPa. It was found that once fully cured and adhered to primed surfaces the resulting technology was able to pass the standard structural glazing norms such as ETAG 002 requirements. Condensation curable silicone compositions generally comprise a minimum of three ingredients, (i) Silicone polymer, typically for example a molecule analogous to the second ingredient used in the preparation of component (a); (ii) a cross-linker molecule which is designed to cross-link the polymer during the curing process to form a cross-linked network creating a cured gel-like and / or elastomeric material and (iii) a catalyst, e.g., a tin (iv) compound or an organic titanate as defined as ingredient (i) herein. However, in this instance, component (a), the titanium-based reaction product described herein, not only appears to render the catalytic nature of the titanium molecules more hydrolytically stable (stable to water) but also because the second component (a) starting ingredient generally has at least two silanol groups per molecule the reaction product has Si-O-Ti or silanol groups available for reaction into the cured product. Hence, when used in or as a curing agent for condensation curable silicone compositions, the titanium-based reaction product resulting from the process for the preparation of component (a) may function as both catalyst and at least partially as the silicone polymer. Component (a) Component (a), the titanium-based reaction product of the two-part silicone elastomeric attachment strip composition herein, is prepared by the reaction of a first and second ingredient. The first ingredient of the process to prepare component (a) is an alkoxy titanium compound having from 2 to 4 alkoxy groups, e.g., Ti(OR)4, Ti(OR)3R1, Ti(OR)2R12or a chelated alkoxy titanium molecule where there are two alkoxy (OR) groups present and a chelate bound twice to the titanium atom; where R is a linear or branched alkyl group having from 1 to 20 carbons, alternatively 1 to 15 carbons, alternatively 1 to 10 carbons, alternatively 1 to 6 carbons and when present R1is an organic group such as an alkyl group having from 1 to 10 carbon atoms, an alkenyl group having from 2 to 10 carbon atoms, an alkynyl group having from 2 to 10 carbon atoms, a cycloalkyl group having from 3 to 10 carbon atoms, or a phenyl group having from 6 to 20 carbon atoms or a mixture thereof. Each R1may optionally contain substituted groups with e.g., one or more halogen group such as chlorine or fluorine. Examples of R1may include, but are not restricted to, methyl, ethyl, propyl, butyl, vinyl, cyclohexyl, phenyl, tolyl group, a propyl group substituted with chlorine or fluorine such as 3,3,3- trifluoropropyl, chlorophenyl, beta-(perfluorobutyl)ethyl or chlorocyclohexyl group. However, typically each R1may be the same or different and is selected from an alkyl group, an alkenyl group or an alkynyl group, alternatively an alkyl group or an alkenyl group, alternatively an alkyl group, in each case having up to 10 carbons, alternatively, up to 6 carbons per group. As mentioned above, R is a linear or branched alkyl group having from 1 to 20 carbons, include but are not restricted to methyl, ethyl, n-propyl, isopropyl, n-butyl, tertiary butyl and branched secondary alkyl groups such as 2, 4-dimethyl-3-pentyl. Suitable examples of the first ingredient when Ti(OR)4, include for the sake of example, tetra methyl titanate, tetra ethyl titanate, tetra n-propyl titanate, tetra n-butyl titanate, tetra t-butyl titanate, tetraisopropyl titanate. When the first ingredient is Ti(OR)3R1, R1is typically an alkyl group and examples include but are not limited to trimethoxy alkyl titanium, triethoxy alkyl titanium, tri n-propoxy alkyl titanium, tri n-butoxy alkyl titanium, tri t-butoxy alkyl titanium and tri isopropoxy alkyl titanate. The first ingredient, used to prepare component (a) of the two-part silicone elastomeric attachment strip composition herein, i.e., the alkoxy titanium compound having from 2 to 4 alkoxy groups, maybe present in an amount of from 0.01 wt. % to 20 wt. % of the total weight of the First ingredient + second ingredient. The second ingredient used to prepare component (a) of the two-part silicone elastomeric attachment strip composition herein is a one or more linear or branched polydiorganosiloxane(s) having at least two terminal silanol groups per molecule. The second ingredient used to prepare component (a) of the two- part silicone elastomeric attachment strip composition herein may comprise one or more oligomer(s) or one or more polymer(s) or a mixture thereof, in each case comprising multiple siloxane units of formula (1) -(R2sSiO(4-s) / 2)- (1) in which each R2is independently an organic group such as a hydrocarbyl group having from 1 to 10 carbon atoms optionally substituted with one or more halogen group such as chlorine or fluorine and s is 0, 1 or 2. In one alternative s is 2 and the linear or branched polydiorganosiloxane backbone is therefore linear although a small proportion of groups where s is 1 may be utilised to enable branching. For example, R2may include alkyl groups such as methyl, ethyl, propyl, butyl, alkenyl groups such as vinyl, propenyl, butenyl, pentenyl and or hexenyl groups, cycloalkyl groups such as cyclohexyl, and aromatic groups such as phenyl, tolyl group. In one alternative, R2may comprise alkyl groups, alkenyl groups and / or phenyl groups such as methyl, ethyl, propyl, butyl, alkenyl groups such as vinyl, propenyl, butenyl, pentenyl and or hexenyl groups, cycloalkyl groups such as cyclohexyl, and aromatic groups such as phenyl, tolyl group. Preferably, the polydiorganosiloxane chain is a polydialkylsiloxane chain, a polyalkylalkenylsiloxane chain or a polyalkylphenylsiloxane chain but co-polymers of any two or more of these may also be useful. When the second ingredient contains a polydialkylsiloxane chain, a polyalkylalkenylsiloxane chain and / or a polyalkylphenylsiloxane chain the alkyl groups usually comprises between 1 and 6 carbons; alternatively the alkyl groups are methyl and / or ethyl groups, alternatively the alkyl groups are methyl groups; the alkenyl groups usually comprises between 2 and 6 carbons; alternatively the alkenyl groups may be vinyl, propenyl, butenyl, pentenyl and or hexenyl groups, alternatively vinyl, propenyl, and / or hexenyl groups. In one alternative the polydiorganosiloxane is a polydimethylsiloxane chain, a polymethylvinylsiloxane chain or a polymethylphenylsiloxane chain, or a copolymer of two or all of these. For the avoidance of doubt a polydiorganosiloxane polymer means a substance composed of a molecule of high molecular weight (generally having a number average molecular weight of greater than or equal to 10,000g / mol comprising a large number of -(R2sSiO(4-s) / 2)- units which show polymer-like properties and the addition or removal of one or a few of the units has a negligible effect on the properties. In contrast a polydiorganosiloxane oligomer is a compound with a regular repeating structure -(R2sSiO(4-s) / 2)- units having too low an average molecular weight e.g., a molecule consisting of a few monomer units, e.g., dimers, trimers, and tetramers are, for example, oligomers respectively composed of two, three, and four monomers. When linear, each terminal group must contain one silanol group. For example, the polydiorganosiloxane maybe dialkylsilanol terminated, alkyl disilanol terminated or trisilanol terminated but is preferably dialkylsilanol terminated. When branched the second ingredient must have at least two terminal silanol (Si-OH) bonds per molecule and as such comprise at least two terminal groups which are dialkylsilanol groups, alkyl disilanol groups and / or trisilanol groups, but typically dialkylsilanol groups. Typically, oligomers and / or polymers provided in the second ingredient for preparing component (a) of the two-part silicone elastomeric attachment strip composition, will have a viscosity in the order of 30 to 300000 mPa.s, alternatively 50 to 100000 mPa.s at 25oC, alternatively 70 to 75,000 mPa.s at 25oC, alternatively 70 to 50,000 mPa.s at 25oC, alternatively 70 to 20,000 mPa.s at 25oC, alternatively 70 to 10,000 mPa.s at 25oC. The viscosity may be measured using any suitable means e.g., a Modular Compact Rheometer (MCR) 302 Anton Paar GmbH of Graz, Austria using the most suitable settings and plates for the viscosity concerned, for example using a 25mm diameter rotational plate with a gap of 0.3 mm at a shear rate of 1s-1. The number average molecular weight (Mn) and weight average molecular weight (Mw) of silicone can also be determined by Gel permeation chromatography (GPC) using polystyrene calibration standards. This technique is a standard technique, and yields values for Mw (weight average), Mn (number average) and polydispersity index (PI) (where PI=Mw / Mn). Mn value provided in this application have been determined by GPC and represent a typical value of the polydiorganosiloxane used. In the present disclosure the number average molecular weight and weight average molecular weight values of component (a) herein may, for example, be determined using a Waters 2695 Separations Module equipped with a vacuum degasser, and a Waters 2414 refractive index detector (Waters Corporation of MA, USA). The analyses may then be performed using certified grade toluene flowing at 1.0 mL / min as the eluent. Data collection and analyses may be performed using Waters Empower GPC software. If not provided by GPC, the Mn may also be obtained from calculation based on the dynamic viscosity of said polydiorganosiloxane. The reaction used to prepare component (a) of the two-part silicone elastomeric attachment strip composition herein, may be undertaken at any suitable temperature but typically commences at room temperature. The temperature may elevate during the reaction and / or stirring and if desired the ingredients may be heated during the reaction. The reaction used to prepare component (a) of the two-part silicone elastomeric attachment strip composition herein takes place under vacuum with a view to removing at least 50 wt. %, alternatively at least 75 wt. % alternatively at least 90% of the total amount of alcoholic by-products generated during the reaction. The above may be determined via several analytical techniques of which the simplest is the determination of weight loss from the reaction product. Without being tied to current understanding, it is believed that the main reaction products of the above reaction when the first ingredient is Ti(OR)4, is a mixture of (RO)nTi((OSiR22)m-OH)4-n(2) Where n is 0, 1 or 2, alternatively 0 or 1, but preferably the major product is where n is 0, i.e., Ti((OSiR22)m-OH)4 (3) Where m is the degree of polymerisation of the second ingredient and is an integer indicative (commensurate) of the viscosity thereof. Similarly, when the first ingredient is substantially Ti(OR)3R1it is believed that the main reaction products of the above reaction when a is 0 or 1, is R1(RO)aTi((OSiR22)m-OH)3-a(4) but preferably the major product is where a is 0, i.e., R1Ti((OSiR22)m-OH)3(5) Where m is the degree of polymerisation of the or each second ingredient (and is an integer indicative (commensurate) of the viscosity of the second ingredient. Optionally, there may be a third ingredient used in the preparation of component (a) of the two-part silicone elastomeric attachment strip composition herein. When present, the third ingredient is a linear or branched polydiorganosiloxane and may be an oligomer or polymer as described for the second ingredient. However, the third ingredient only has one terminal silanol group per molecule for use in the reaction described above to form a Si-O-Ti bond with the first ingredient. The other terminal group(s) of the third ingredient contain no silanol groups. The terminal groups containing no silanol groups may comprise R2groups as defined above, alternatively a mixture of alkyl and alkenyl R2groups, alternatively alkyl R2groups. Examples include trialkyl termination e.g., trimethyl or triethyl termination or dialkylalkenyl termination, e.g., dimethylvinyl or diethyl vinyl or methylethylvinyl termination or the like. Typically the third ingredient used in the preparation of component (a) of the two-part silicone elastomeric attachment strip composition herein will also have a viscosity analogous to that of the second ingredient, in the order of 30 to 300000 mPa.s, alternatively 50 to 100000 mPa.s at 25oC, alternatively 70 to 75,000 mPa.s at 25oC, alternatively 70 to 50,000 mPa.s at 25oC, alternatively 70 to 20,000 mPa.s at 25oC, alternatively 70 to 10,000 mPa.s at 25oC. The viscosity may be measured using any suitable means e.g., a Modular Compact Rheometer (MCR) 302 Anton Paar GmbH of Graz, Austria using the most suitable settings and plates for the viscosity concerned, for example using a 25mm diameter rotational plate with a gap of 0.3 mm at a shear rate of 1s-1. The third ingredient may be present in an amount of up to 75 wt. % of the combination of the weight of the first, second and third ingredients, whereby the third ingredient replaces the equivalent proportion of the second ingredient. However, preferably the third ingredient when present is present in an amount of no more than 50%, alternatively no more than 25% of the first, second and third ingredients. When the third ingredient is present one or more silanol groups in structures (2), (3), (4) or (5) may be replaced by an R2group, alternatively an alkyl group or an alkenyl group, alternatively an alkyl group. For example, in the case of structure (2) the reaction product may be that shown below in structure (2a): (RO)nTi ((OSiR22)m- R2)p((OSiR22)m-OH)4-n-p(2a) Where n is 0, 1 or 2, alternatively 0 or 1, p is 0, 1 or 2, alternatively 0 or 1, and n +p is less than or equal to 4 and m is as previously defined. It is preferred not to include the third ingredient as a reactant in the preparation of component (a) of the two-part silicone elastomeric attachment strip composition herein as when catalysts of the type depicted in structures (2), (3), (4) or (5) are present the terminal silanol groups are potentially available for participation in the formation of the cured silicone network, which makes them useful in the fully formulated elastomers. This is clearly less likely to be the case when greater amounts of the third ingredient are used as a starting ingredient in the process to make the titanium-based reaction product which can be used as component (a) in the two-part silicone elastomeric attachment strip compositions described herein. However, the presence of some of the third ingredient in the starting materials may be useful to assist in obtaining the required modulus of elastomers cured using the product of the process described herein. When the starting ingredients in the process used for the preparation of component (a) of the two-part silicone elastomeric attachment strip composition herein are the first and second ingredients, the molar ratio of silanol groups : titanium may be any suitable molar ratio equal to or greater than 2 : 1. However, it is preferred for the molar ratio to be within the range of from 5 : 1 to 15 : 1 alternatively from 7 : 1 to 15 : 1, alternatively from at least 8 : 1 to 11 : 1. Lower molar ratios seem to lead to the presence of more viscous reaction product and less first ingredient present resulting in slower gelling times. The total silanol (Si-OH) molar content (i.e., of Si-OH bonds) of component (a) is calculated for 100 g of the first and second ingredients used to make component (a). The silanol molar content related to the second ingredient for making component (a) is equal to the amount in grams (g) of silanol containing polymer in 100g of the first and second ingredients divided by the number average molecular weight of the second ingredient multiplied by the average number of silanol functions present in the second ingredient, typically 2. If there are several silanol functional linear or branched polydiorganosiloxanes in the starting ingredients, the sum of the molar content of Si-OH bonds for each polymer is determined and then the cumulative total from all the linear or branched polydiorganosiloxanesis added together to constitute the total silanol molar content (i.e. content of silanol bonds)in the formulation. The molar amount of any starting ingredient used in the preparation of component (a) was determined using the following calculation: [Weight in parts of the ingredient x 100] [sum of all parts of the starting ingredients x MW of the ingredient] Hence, merely for example, when ingredient 1 is tetra n-butyl titanate (TnBT), if ingredient 1 and ingredient 2 were mixed in a weight ratio of 10:1, i.e., 10 parts of ingredient 2 to every one part by weight of ingredient 1, given the molecular weight of TnBT is 340; the calculation would be. [Weight in parts of TnBT (1) x 100] [sum of all parts of the starting ingredients (11) x 340] =0.0267 mole of catalyst per 100g of the two-part silicone elastomeric attachment strip composition. In one embodiment of the process used in the preparation of component (a) of the two-part silicone elastomeric attachment strip composition herein, the first ingredient is added to the second ingredient, or when the third ingredient is present, the first ingredient is added to a mixture of the second and third ingredients. In an alternative embodiment used in the preparation of component (a) of the two-part silicone elastomeric attachment strip composition herein, the second ingredient may be introduced into the first ingredient. This embodiment is less convenient than the above because titanates of the type used as the first ingredient, from which volatile alcohols (R-OH) are generated in accordance with chemical reactions (6) below, are generally flammable due to the moisture from environment because it will usually (but not always) contain some alcohol residues. The flash point of the titanium catalyst depends on the alcohol flammability. Ti-OR + H2O (moisture from the air) -> Ti-OH + R-OH Ti-OR + Si-OH -> Ti-O-Si + R-OH (6) Hence, this method will require an explosion proof manufacturing process and the second ingredient is introduced into the first ingredient in a gradual measured manner. This route is likely to lead, at least initially, to a more concentrated catalyst until gradually the content of the second ingredient is increased. This embodiment is also less favoured because it is more difficult to remove the alcoholic by-products as successfully and the content of the second ingredient is generally much larger than the first ingredient in weight and volume. It was found however, that there was no need for complicated separation techniques to be used to isolate specific titanium species as component (a) of the two-part silicone elastomeric attachment strip composition as the reaction product works very well without separation. Component (b) of the two-part silicone elastomeric attachment strip composition Component (b) of the two-part silicone elastomeric attachment strip composition is at least one linear or branched polydiorganosiloxane polymer(s) having at least two terminal silanol groups per molecule alternatively at least 3 hydroxyl groups per molecule. Component (b) may thus have two but alternatively has three or more silicon-bonded condensable (preferably hydroxyl and / or hydrolysable) groups per molecule which are reactive with the silanol groups in component (a). In one embodiment, component (b) of the two-part silicone elastomeric attachment strip composition herein is an organopolysiloxane polymer having at least two hydroxyl groups per molecule of the formula: (HO)3-n’R3n’Si-(Z)d –(O)q- (R4ySiO(4-y) / 2)z –(SiR42- Z)d-Si-R3n’ (OH)3-n’ (7) in which each R3is an alkyl, alkenyl or aryl group, each R4is independently an OH group, alkyl group, alkenyl group or aryl group (i.e., OH or R3) and Z is a divalent organic group; d is 0 or 1, q is 0 or 1 and d+ q = 1; n’ is 0, 1, 2 or 3, y is 0, 1 or 2, and preferentially 2 and z is an integer such that said organopolysiloxane polymer has a viscosity of from 50 to 150,000 mPa.s at 25oC, alternatively 50 to 100000 mPa.s at 25oC, alternatively 70 to 75,000 mPa.s at 25oC, alternatively 70 to 50,000 mPa.s at 25oC, alternatively 70 to 20,000 mPa.s at 25oC, alternatively 70 to 10,000 mPa.s at 25oC. The value of z is therefore an integer enabling (commensurate with) such a viscosity, alternatively z is an integer from 100 to 5000. Whilst y is 0, 1 or 2, substantially y= 2, e.g., at least 90% alternatively 95% of R4ySiO(4-y) / 2 groups are characterized with y = 2. For the avoidance of doubt when either or both n’ values is / are 3 an equivalent number of R4groups per molecule must be OH. The viscosity may be measured using any suitable means e.g., a Modular Compact Rheometer (MCR) 302 from Anton Paar GmbH of Graz, Austria using the most suitable settings and plates for the viscosity concerned, for example using a 25mm diameter rotational plate with a gap of 0.3 mm at a shear rate of 1s-1. Each R3is individually selected from alkyl groups, alternatively alkyl groups having from 1 to 10 carbon atoms, alternatively from 1 to 6 carbon atoms, alternatively 1 to 4 carbon atoms, alternatively methyl or ethyl groups; alkenyl groups alternatively alkenyl groups having from 2 to 10 carbon atoms, alternatively from 2 to 6 carbon atoms such as vinyl, allyl and hexenyl groups; aromatic groups, alternatively aromatic groups having from 6 to 20 carbon atoms, substituted aliphatic organic groups such as 3,3,3- trifluoropropyl groups aminoalkyl groups, polyaminoalkyl groups, and / or epoxyalkyl groups. Each R4is individually selected from the group consisting of -OH or an alkyl, alkenyl or aryl group i.e., (OH or R3) with the proviso that when either n’ is 3 the terminal OH is replaced by an R4group which is a hydroxyl (OH) group. It is possible that some R4groups may be siloxane branches off the polymer backbone which branches may have terminal groups as hereinbefore described. Most preferred each R4is methyl. Hence, when both n’s are 3, R4must include at least two OH groups. Each Z is independently selected from an alkylene group having from 1 to 10 carbon atoms. In one alternative each Z is independently selected from an alkylene group having from 2 to 6 carbon atoms; in a further alternative each Z is independently selected from an alkylene group having from 2 to 4 carbon atoms. Each alkylene group may for example be individually selected from an ethylene, propylene, butylene, pentylene and / or hexylene group. Additionally, n’ is 0, 1, 2 or 3, d is 0 or 1, q is 0 or 1 and d+ q = 1. In one alternatively when q is 1, n’ is 1 or 2. Component (b) when an organopolysiloxane polymer can be a single siloxane represented by Formula (7) or it can be mixtures of organopolysiloxane polymers represented by the aforesaid formula. Hence, the term "siloxane polymer mixture" in respect to component (b) when an organopolysiloxane polymer is meant to include any individual organopolysiloxane polymer or mixtures of organopolysiloxane polymer. The Degree of Polymerization (DP), (i.e., in the above formula substantially z), is usually defined as the number of monomeric units in a macromolecule or polymer or oligomer molecule of silicone. Synthetic polymers invariably consist of a mixture of macromolecular species with different degrees of polymerization and therefore of different molecular weights. There are different types of average polymer molecular weight, which can be measured in different experiments. The two most important are the number average molecular weight (Mn) and the weight average molecular weight (Mw). The Mn and Mw of a silicone polymer can be determined by Gel permeation chromatography (GPC) using polystyrene calibration standards. with precision of about 10-15%. This technique is standard and yields Mw, Mn and polydispersity index (PI). The degree of polymerisation (DP) =Mn / Mu where Mn is the number-average molecular weight coming from the GPC measurement and Mu is the molecular weight of a monomer unit. PI=Mw / Mn. The DP is linked to the viscosity of the polymer via Mw, the higher the DP, the higher the viscosity. When component (b) of the two-part silicone elastomeric attachment strip composition is an organopolysiloxane polymer as described above, it may be present in the two-part silicone elastomeric attachment strip composition in an amount of from 1 to 95 wt. % of the two-part silicone elastomeric attachment strip composition, alternatively 5 to 90 wt. %, alternatively 10 to 80 wt. % by weight of the two-part silicone elastomeric attachment strip composition. The total wt. % of any one composition is 100 wt. %. The second part of the two-part silicone elastomeric attachment strip composition The second part of the two-part silicone elastomeric attachment strip composition comprises components (a’) and (b’) where: (a’) is at least one trimethoxy terminated polysiloxane; and (b’) is a bis(trialkoxysilyl)alkane having from 8 to 20 carbons per molecule, a trialkoxyphenylsilane having from 8 to 20 carbons per molecule; or a mixture thereof. Component (a’) Component (a’) in the second part of the two-part silicone elastomeric attachment strip composition is at least one trimethoxy terminated polysiloxane. Component (a’) may be linear or branched polydiorganosiloxane polymer(s). In one embodiment, component (a’) of the two-part silicone elastomeric attachment strip composition herein is an organopolysiloxane polymer of the formula: (R11O)3’Si-(Z)d–(O)q- (R8ySiO(4-y) / 2)z–(S-iR82-Z)d-Si- (O R11)3(8) in which each R11is independently an alkyl group having from 1 to 6 carbons, and each R8is independently an (OR11) group, alkyl group, alkenyl group or aryl group and Z is a divalent organic group; d is 0 or 1, q is 0 or 1 and d+ q = 1; y is 0, 1 or 2, and preferentially 2 and z is an integer such that said organopolysiloxane polymer has a viscosity of from 50 to 150,000 mPa.s at 25oC, alternatively 50 to 100 000 mPa.s at 25oC, alternatively 70 to 75,000 mPa.s at 25oC, alternatively 70 to 50,000 mPa.s at 25oC, alternatively 70 to 20,000 mPa.s at 25oC, alternatively 70 to 10,000 mPa.s at 25oC. The value of z is therefore an integer enabling (commensurate with) such a viscosity, alternatively z is an integer from 100 to 5000. Whilst y is 0, 1 or 2, substantially y= 2, e.g., at least 90% alternatively 95% of R8ySiO(4-y) / 2groups are characterized with y = 2. The viscosity may be measured using any suitable means e.g., a Modular Compact Rheometer (MCR) 302 from Anton Paar GmbH of Graz, Austria using the most suitable settings and plates for the viscosity concerned, for example using a 25mm diameter rotational plate with a gap of 0.3 mm at a shear rate of 1s-1. Each R8is individually selected from alkyl groups, alternatively alkyl groups having from 1 to 10 carbon atoms, alternatively from 1 to 6 carbon atoms, alternatively 1 to 4 carbon atoms, alternatively methyl or ethyl groups; alkenyl groups alternatively alkenyl groups having from 2 to 10 carbon atoms, alternatively from 2 to 6 carbon atoms such as vinyl, allyl and hexenyl groups; aromatic groups, alternatively aromatic groups having from 6 to 20 carbon atoms, substituted aliphatic organic groups such as 3,3,3- trifluoropropyl groups aminoalkyl groups, polyaminoalkyl groups, and / or epoxyalkyl groups. Each R8is preferably individually selected from an alkyl group the group having from 1 to 6 carbons for example methyl, ethyl, propyl, n-butyl, t-butyl and n-hexyl, alternatively methyl, ethyl, propyl, n-butyl or t-butyl: alternatively, methyl, ethyl, propyl, alternatively methyl. Each Z is independently selected from an alkylene group having from 1 to 10 carbon atoms. In one alternative each Z is independently selected from an alkylene group having from 2 to 6 carbon atoms; in a further alternative each Z is independently selected from an alkylene group having from 2 to 4 carbon atoms. Each alkylene group may for example be individually selected from an ethylene, propylene, butylene, pentylene and / or hexylene group. Additionally, d is 0 or 1, q is 0 or 1 and d+ q = 1. Component (a’) when an organopolysiloxane polymer can be a single siloxane represented by Formula (8) or it can be mixtures of organopolysiloxane polymers represented by the aforesaid formula. Hence, the term "siloxane polymer mixture" in respect to component (a’) when an organopolysiloxane polymer is meant to include any individual organopolysiloxane polymer or mixtures of organopolysiloxane polymer. When component (a’) of the two-part silicone elastomeric attachment strip composition is an organopolysiloxane polymer as described above, it may be present in the two-part silicone elastomeric attachment strip composition in an amount of from 1 to 95 wt. % of the two-part silicone elastomeric attachment strip composition, alternatively 5 to 90 wt. %, alternatively 10 to 80 wt. % by weight the two- part silicone elastomeric attachment strip composition. The total wt. % of any one composition is 100 wt. %. Component (b’) of the two-part silicone elastomeric attachment strip composition Component (b’) of the two-part silicone elastomeric attachment strip composition is a bis(trialkoxysilyl)alkane having from 8 to 20 carbons per molecule, or a trialkoxyphenylsilane having from 8 to 20 carbons per molecule or a mixture thereof. The bis(trialkoxysilyl)alkane having from 8 to 20 carbons per molecule may be linear branched or cyclic. The alkoxy groups in the bis(trialkoxysilyl)alkane may be the same or different and typically have from 1 to 4 carbons per alkoxy group, for example, methoxy, ethoxy, propoxy, n-butoxy and t-butoxy groups; alternatively methoxy or ethoxy groups, alternatively methoxy groups. The “alkane” group may have from 2 to 10 carbons and is generally linear but may be branched, examples include pentane, hexane and heptane; for example, 1,6-bis (trimethoxysilyl)hexane (alternatively known as hexamethoxydisilylhexane), 1,5-bis (trimethoxysilyl)pentane and 1,7-bis (trimethoxysilyl)heptane. The trialkoxyphenyl silane has the structure: Where each R7may be the same or diff s defined above with the trialkoxyphenyl silane having from 8 to 20 carbons per molecu e; or a mx ure thereof. It is a requirement of the present disclosure that the two-part silicone elastomeric attachment strip composition described herein has the following molar ratio: i.e., the molar ratio of Si-OH bonds : Si-alkoxy bonds is from 0.1 : 1 to 0.5 : 1. The molar content of Si-alkoxy bonds is calculated for 100 g of the composition considering components, which contain Si-alkoxy groups, e.g., components (a’) and (b’). The molar content of Si-alkoxy bonds related to component (a’) is equal to the amount in grams (g) of Si-alkoxy containing polymer in 100g of the composition divided by the number average molecular weight of component (a’) multiplied by the average number of Si-alkoxy functions present in component (a’) typically 6. If there are several functional linear or branched polydiorganosiloxanes in the starting ingredients, the sum of the molar content of each polymer is determined based on their number average molecular weight Mn and then the cumulative total from all the linear or branched polydiorganosiloxanes, is added together to constitute the molar content of Si-alkoxy bonds in the formulation. Component (c) of the two-part silicone elastomeric attachment strip composition Component (c) of the two-part silicone elastomeric attachment strip composition is one or more fillers, comprising fumed silica, precipitated silica, precipitated calcium carbonate or a mixture thereof, which filler(s) is / are optionally hydrophobically treated and function as a source of water. These fillers are reinforcing fillers. These fillers are preferably introduced into the composition in a finely divided form. Component (c) may be present in the first part composition, in the second part composition or both the first part composition and the second part composition. Alternatively, some or all of component (c) is contained in the first part composition. Typically, the surface area of reinforcing filler is at least 15 m² / g in the case of precipitated calcium carbonate measured in accordance with the BET method in accordance with ISO 9277: 2010, alternatively 15 to 50 m² / g, alternatively, 15 to 25 m² / g. The silica reinforcing fillers have a typical surface area of at least 50 m² / g. The silica filler may be precipitated silica and / or fumed silica. In the case of high surface area fumed silica and / or high surface area precipitated silica, these may have surface areas of from 75 to 450 m² / g measured using the BET method in accordance with ISO 9277: 2010, alternatively of from 100 to 400 m² / g using the BET method in accordance with ISO 9277: 2010. Typically, the reinforcing fillers of component (c) are present in the two-part silicone elastomeric attachment strip composition in an amount of from about 5 to 45 wt. % of the two-part silicone elastomeric attachment strip composition, alternatively from about 5 to 40 wt. % of the two-part silicone elastomeric attachment strip composition, alternatively from about 5 to 35 wt. % of the two-part silicone elastomeric attachment strip composition, depending on the chosen filler. The reinforcing filler may be hydrophobically treated, for example, with one or more aliphatic acids, e.g., a fatty acid such as stearic acid or a fatty acid ester such as a stearate, or with organosilanes, organosiloxanes, or organosilazanes hexaalkyl disilazane or short chain siloxane diols to render the reinforcing filler(s) hydrophobic and therefore easier to handle and obtain a homogeneous mixture with the other adhesive components. The surface treatment of the fillers makes them easily wetted by components in the first part composition, in the second part composition or both the first part composition and the second part composition. These surface modified fillers do not clump and can be homogeneously incorporated into the first part composition, in the second part composition or both the first part composition and the second part composition as required. Optional Additives The two-part silicone elastomeric attachment strip composition as hereinbefore described may comprise a variety of additives. The additives may include, but are not limited to, adhesion promoters, non- reinforcing fillers, rheological additives, plasticizers and / or extenders, pigments & colorants, UV absorbers, antioxidants, UV and / or light stabilizers and biocides. Adhesion Promoter Suitable adhesion promoters may comprise alkoxysilanes of the formula R14hSi(OR15)(4-h) where subscript h is 1, 2, or 3, alternatively h is 3. Each R14is independently a monovalent organofunctional group. R14can be an epoxy functional group such as glycidoxypropyl or (epoxycyclohexyl)ethyl, an amino functional group such as aminoethylaminopropyl or aminopropyl, a methacryloxypropyl, a mercapto functional group such as mercaptopropyl or an unsaturated organic group. Each R15is independently an unsubstituted, saturated hydrocarbon group of at least 1 carbon atom. R15may have 1 to 4 carbon atoms, alternatively 1 to 2 carbon atoms. R15is exemplified by methyl, ethyl, n-propyl, and iso- propyl. When present adhesion promoters will be present in an amount of from 0.01% to 2wt. %, alternatively 0.05 to 2 wt. %, alternatively 0.1 to 1 wt. % of adhesion promoter based on the weight of the total composition when mixed. When present the hydrolysable (alkoxy groups of the adhesion promoter will be included in in the calculations when determining the ratios hereinbefore described. Examples of suitable adhesion promoters include glycidoxypropyltrimethoxysilane and a combination of glycidoxypropyltrimethoxysilane with an aluminium chelate or zirconium chelate. Examples of adhesion promoters may be found in U.S. Patent 4,087,585 and U.S. Patent 5,194,649. Preferably, the speed of hydrolysis of the adhesion promoter should be lower than the speed of hydrolysis of the cross-linker in order to favour diffusion of the molecule towards the substrate rather than its incorporation in the product network. Non-reinforcing fillers Non-reinforcing fillers, which might be used alone or in addition to the above include aluminite, calcium sulphate (anhydrite), gypsum, nepheline, syenite, quartz, ground calcium carbonate, calcium sulphate, magnesium carbonate, clays such as kaolin, aluminium trihydroxide, magnesium hydroxide (brucite), graphite, copper carbonate, e.g., malachite, nickel carbonate, e.g., zarachite, barium carbonate, e.g., witherite and / or strontium carbonate e.g., strontianite. Silicates from the group consisting of olivine group; garnet group; aluminosilicates; ring silicates; chain silicates; and sheet silicates. The olivine group comprises silicate minerals, such as but not limited to, forsterite and Mg2SiO4. The garnet group comprises ground silicate minerals, such as but not limited to, pyrope; Mg3Al2Si3O12; grossular; and Ca2Al2Si3O12. Aluminosilicates comprise ground silicate minerals, such as but not limited to, sillimanite; Al2SiO5; mullite; 3Al2O3.2SiO2; kyanite; and Al2SiO5. The ring silicates group comprises silicate minerals, such as but not limited to, cordierite and Al3(Mg,Fe)2[Si4AlO18]. The chain silicates group comprises ground silicate minerals, such as but not limited to, wollastonite and Ca[SiO3]. The sheet silicates group comprises silicate minerals, such as but not limited to, mica; K2AI14[Si6Al2O20](OH)4; pyrophyllite; Al4[Si8O20](OH)4; talc; Mg6[Si8O20](OH)4; serpentine for example, asbestos; Kaolinite; Al4[Si4O10](OH)8; and vermiculite. The non-reinforcing fillers may also be hydrophobically treated as described above. Rheology modifiers Rheology modifiers which may be incorporated in the two-part silicone elastomeric attachment strip composition as described above include silicone organic co-polymers such as those described in EP0802233 based on polyols of polyethers or polyesters; non-ionic surfactants selected from the group consisting of polyethylene glycol, polypropylene glycol, ethoxylated castor oil, oleic acid ethoxylate, alkylphenol ethoxylates, copolymers or ethylene oxide and propylene oxide, and silicone polyether copolymers; as well as silicone glycols. For some systems these rheology modifiers, particularly copolymers of ethylene oxide and propylene oxide, and silicone polyether copolymers, may enhance the adhesion to substrates, particularly plastic substrates. One or more plasticizer(s), one or more extender(s) or a mixture thereof The two-part silicone elastomeric attachment strip composition as described above may also include one or more plasticizer(s), one or more extender(s) or a mixture thereof (g). These may be in the form of silicone or organic fluids which are unreactive with organopolysiloxane polymer(s) (a) and / or crosslinker(s) (b) and / or catalyst (d). If present the plasticizer or extender content will be present in an amount of from 5 to 30 wt. % of the composition, alternatively from 5 to 10 wt. % or the composition. Examples of non-reactive silicone fluids useful as plasticizers include polydiorganosiloxanes such as polydimethylsiloxane having terminal triorganosiloxy groups wherein the organic substituents are, for example, methyl, vinyl or phenyl or combinations of these groups. Such polydimethylsiloxanes can for example have a viscosity of from about 5 to about 100,000 mPa.s at 25oC (measured as described above). Alternatively compatible organic plasticisers may be utilised additionally to or instead of the silicone fluid plasticiser. These may include dialkyl phthalates wherein the alkyl group may be linear and / or branched and contain from six to 20 carbon atoms such as dioctyl, dihexyl, dinonyl, didecyl, diallanyl and other phthalates, and analogous adipate, azelate, oleate and sebacate esters; polyols such as ethylene glycol and its derivatives; and organic phosphates such as tricresyl phosphate and / or triphenyl phosphates. Examples of extenders for use in compositions herein include mineral oil based (typically petroleum based) paraffinic hydrocarbons, mixtures of paraffinic and naphthenic hydrocarbons, paraffin oils comprising cyclic paraffins and non-cyclic paraffins and hydrocarbon fluids containing naphthenics, polycyclic naphthenics and paraffins, or polyalkylbenzenes such as heavy alkylates (alkylated aromatic materials remaining after distillation of oil in a refinery). Examples of such extenders are discussed in GB2424898 the content of which is hereby enclosed by reference. Pigments and / or colorants The two-part silicone elastomeric attachment strip composition as described above may further comprise one or more pigments and / or colorants. The pigments and / or colorants may be coloured, white, black, metal effect, and luminescent e.g., fluorescent or phosphorescent. Pigments are utilized to colour the composition as required. Any suitable pigment may be utilized providing it is compatible with the composition herein. In two-part silicone elastomeric attachment strip composition s as described above pigments and / or coloured (non-white) fillers e.g., carbon black may be utilized in the catalyst package to colour the end sealant product. Suitable white pigments and / or colorants include titanium dioxide, zinc oxide, lead oxide, zinc sulfide, lithophone, zirconium oxide, and antimony oxide. Suitable non-white inorganic pigments and / or colorants include, but are not limited to, iron oxide pigments such as goethite, lepidocrocite, hematite, maghemite, and magnetite black iron oxide, yellow iron oxide, brown iron oxide, and red iron oxide; blue iron pigments; chromium oxide pigments; cadmium pigments such as cadmium yellow, cadmium red, and cadmium cinnabar; bismuth pigments such as bismuth vanadate and bismuth vanadate molybdate; mixed metal oxide pigments such as cobalt titanate green; chromate and molybdate pigments such as chromium yellow, molybdate red, and molybdate orange; ultramarine pigments; cobalt oxide pigments; nickel antimony titanates; lead chrome; carbon black (when present, carbon black will function as both a non-reinforcing filler and colorant); lampblack, and metal effect pigments such as aluminium, copper, copper oxide, bronze, stainless steel, nickel, zinc, and brass. Suitable organic non-white pigments and / or colorants include phthalocyanine pigments, e.g., phthalocyanine blue and phthalocyanine green; monoarylide yellow, diarylide yellow, benzimidazolone yellow, heterocyclic yellow, DAN orange, quinacridone pigments, e.g., quinacridone magenta and quinacridone violet; organic reds, including metallized azo reds and nonmetallized azo reds and other azo pigments, monoazo pigments, diazo pigments, azo pigment lakes, β-naphthol pigments, naphthol AS pigments, benzimidazolone pigments, diazo condensation pigment, isoindolinone, and isoindoline pigments, polycyclic pigments, perylene and perinone pigments, thioindigo pigments, anthrapyrimidone pigments, flavanthrone pigments, anthanthrone pigments, dioxazine pigments, triarylcarbonium pigments, quinophthalone pigments, and diketopyrrolo pyrrole pigments. Typically, the pigments and / or colorants, when particulates, have average particle diameters in the range of from 10 nm to 50 µm, preferably in the range of from 40 nm to 2 µm. The pigments and / or colorants when present are present in the range of from 2, alternatively from 3, alternatively from 5 to 20 wt. % of the composition. Antioxidant Any suitable antioxidant(s) may be utilised, if deemed required. Examples may include: ethylene bis (oxyethylene) bis(3-tert-butyl-4-hydroxy-5(methylhydrocinnamate) 36443-68-2; tetrakis[methylene(3,5- di-tert-butyl-4-hydroxy hydrocinnamate)]methane 6683-19-8; octadecyl 3,5-di-tert-butyl-4- hydroxyhyrocinnamate 2082-79-3; N,N’-hexamethylene-bis (3,5-di-tert-butyl-4- hydroxyhyrocinnamamide) 23128-74-7; 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid,C7-9 branched alkyl esters 125643-61-0; N-phenylbenzene amine, reaction products with 2,4,4-trimethylpentene 68411- 46-1; e.g., anti-oxidants sold under the Irganox®name from BASF. UV and / or light stabilizers UV and / or light stabilizers may include, for the sake of example include benzotriazole, ultraviolet light absorbers and / or hindered amine light stabilizers (HALS) such as the TINUVIN®product line from Ciba Specialty Chemicals Inc. Biocides Biocides may additionally be utilized in the two-part silicone elastomeric attachment strip composition if required. It is intended that the term “biocides” includes bactericides, fungicides and algicides, and the like. Suitable examples of useful biocides, which may be utilized in compositions as described herein, include, for the sake of example: Carbamates such as methyl-N-benzimidazol-2-ylcarbamate (carbendazim) and other suitable carbamates, 10,10’-oxybisphenoxarsine, 2-(4-thiazolyl)-benzimidazole, N-(fluorodichloromethylthio)phthalimide, diiodo methyl p-tolyl sulfone, if appropriate in combination with a UV stabilizer, such as 2,6-di(tert-butyl)-p-cresol, 3-iodo-2-propinyl butylcarbamate (IPBC), zinc 2-pyridinethiol 1-oxide, triazolyl compounds and isothiazolinones, such as 4,5-dichloro-2-(n-octyl)-4- isothiazolin-3-one (DCOIT), 2-(n-octyl)-4-isothiazolin-3-one (OIT) and n-butyl-1,2-benzisothiazolin-3- one (BBIT). Other biocides might include for example Zinc Pyridinethione, 1-(4-Chlorophenyl)-4,4- dimethyl-3-(1,2,4-triazol-1-ylmethyl)pentan-3-ol and / or 1-[[2-(2,4-dichlorophenyl)-4-propyl-1,3- dioxolan-2-yl] methyl]-1H-1,2,4-triazole. The fungicide and / or biocide may suitably be present in an amount of from greater than 0 to 0.3wt. % of the composition and may be present in an encapsulated form where required such as described in EP2106418. The two-part silicone elastomeric attachment strip composition is stored before use in two-parts to prevent premature cure. Reaction product (a) and component (b) are present in the first part composition, referred to hereafter as Part A and components (a’) and (b’) are present in the second part composition, referred to hereafter as Part B. As previously discussed, component (c) may be present in Part A and / or Part B and is preferably at least partially present in Part A. The part A composition would in a standard composition comprise a polymer and a catalyst but as previously discussed the titanium-based reaction product (component (a)) herein effectively functions as both polymer and catalyst. The Part B composition effectively comprises the materials which function as cross-linkers and as such the two-part silicone elastomeric attachment strip composition does not cure until Parts A and B have been thoroughly mixed together. Part A and Part B of the two-part silicone elastomeric attachment strip composition can be mixed in any suitable weight ratio. The Part A : part B weight ratio when mixed together depends on the cross-linker content in Part B and which part the filler component (c) is present in Part A and Part B may be mixed in a 1 : 1 weight ratio, whereas if most or all of filler component (c) is in Part A the weight ratio will be less equal. Hence the Part A : part B weight ratio may tend to be between 15: 1 to 1 : 1, particularly when component (c) is mainly present in Part A, alternatively between 10: 1 to 1:1, alternatively 5: 1 to 1: 1. However, the weight ratio of the mixture can be varied further if desired, especially if a proportion or all the filler component (c) is present in Part B. All composition amounts in wt. % are provided with a view of the said total wt. % of the respective composition to which they refer being 100 wt. %. The silicone elastomeric attachment strip The silicone elastomeric attachment strip which is the cured product of the above composition has several advantages over previous strip solutions. Being made from a silicone composition it is UV resistant and consequently does not yellow with age. It is a translucent flexible elastomeric material and can be colored using the pigments and colorants described above. It provides improved adhesion between substrates and as such the silicone elastomeric attachment strip does not require as much of the strip to be present between the substrates as previous alternatives. As indicated elsewhere it is not a pressure sensitive adhesive. Such silicone elastomeric attachment strips as described herein are, after cure, not sticky to the touch, unlike pressure sensitive adhesive materials. Adhesion is provided through a chemical interaction between the silicone elastomeric attachment strip and pre-applied primers on the substrate surfaces. The silicone elastomeric attachment strip described herein may be provided on a roll or in the form of strips separate from both substrates or may be provided to a customer pre-applied so that one face of the silicone elastomeric attachment strip is provided with the strip adhered to it and the other side of the strip is optionally provided with a release layer which can be easily removed prior to adhesion to the second substrate. When provided in this form a suitable primer can be applied onto the first substrate surface. Typically, this will be e.g., a metal, e.g., aluminum frame. The primer is left for several minutes e.g., about 5 minutes on the substrate to dry and / or react with the substrate surface before the composition is applied onto the primed region of the first substrate. The composition is left to cure if applied in an uncured state or the silicone elastomeric attachment strip is left for several days in order to adhere to the first substrate. If desired the side of the strip to be brought into contact with the second substrate may have a release liner provided which is removed prior to application of the silicone elastomeric attachment strip on to the primed second substrate for adhesion thereto. Once removed (if present) the silicone elastomeric attachment strip and the second substrate can be aligned and attached to a second substrate surface e.g., glass. In the method of preparing a silicone elastomeric attachment strip, in step (A) the first part composition is prepared by mixing components (a) and (b) as described previously; step (B) separately prepares a second part composition by mixing components (a’) and (b’) as defined previously. Component (c) the reinforcing is mixed into the first part composition, the second part composition or both the first part composition and the second part composition. Typically, at least a proportion of component (c) is introduced into the Part A composition. After Parts A and B have been independently prepared, they may be stored for a period until required for making a silicone elastomeric attachment strip as described herein. The weight ratio of the Parts A and B will depend on which part(s) contains the filler (c) and the optional additives, if present and can range from 15 : 1 to 1 : 15 but typically a weight ratio of from silicone elastomeric attachment strip is in the region of 1 : 1, if possible, for ease of mixing on the site where the strips are being made and applied. To ensure the elastomeric attachment strip has the desired features as described herein it is very important to ensure that composition has a molar ratio of Si-OH bonds : Si-alkoxy bonds of from 0.1 : 1 to 0.5 : 1. Typically this is achieved when making the Part A and Part B compositions and is an important reason to ensure Parts A and B are mixed in the correct proportions when preparing the strip. In the case of Part A, component (a), the titanium-based reaction product, may be produced as hereinbefore described using a suitable mixer or compounder apparatus such as a 50-liter compounder such as for the sake of example (but not limited to) a Neulinger 50-liter compounder. A required amount of ingredient (ii) a linear or branched polydiorganosiloxane polymer having at least two terminal silanol groups per molecule, for example a dimethylsilanol terminated polydimethylsiloxane having a viscosity of from 500 to 5000mPa.s at 25oC, alternatively from 500 to 2500 mPa.s at 25oC, alternatively from 500 to 1500 mPa.s at 25oC and a predetermined amount of an alkoxy titanium compound having from 2 to 4 alkoxy groups such as tetraisopropoxy titanium may be introduced together into the compounder and may then be mixed together for a predetermined time of from 90 seconds to 5 minutes, alternatively from 90 seconds to 4 minutes, alternatively from 90 seconds to 3 minutes. In one embodiment mixing may be carried out at a low speed with a view to inducing a high shear. This may be achieved by using a dissolver disk mixing element. The resulting mixture may then be mixed for a further predetermined time of from 90 seconds to 5 minutes, alternatively from 90 seconds to 4 minutes, alternatively from 90 seconds to 3 minutes using e.g., a planetary mixing element in combination with the aforementioned dissolver disc mixing element. The dissolver disc mixing element may be operated at a much faster rotational speed than the planetary mixing element dissolver disc mixing element. Hence, the dissolver disc mixing element may be rotated at from, for example, 1000 to 3000 rpm with the planetary mixing element being rotated at a much smaller speed of from 20 to 200rpm. Vacuum may be applied during the second mixing period and the temperature may be allowed to increase due to shear mixing to a temperature of from 80 to 150oC, alternatively to a temperature of from 80 to 125oC to a temperature of from 80 to 110oC. The resulting mixture is typically further mixed under dynamic vacuum for an extended period of from 1 hour to 4 hours, alternatively from 1 hour to 3 hours; alternatively, from 1 hour to 2.5 hours. The final product is then cooled or allowed to cool and a final viscosity measurement taken. All viscosity measurements above may be carried out using a suitable rheometer or viscometer at about room temperature (25oC) such as a Modular compact rheometer (MCR 302 from Anton Paar GmbH of Graz, Austria. Once component (a) has been prepared the first part composition (hereafter referred to as Part A and the second part composition (hereafter referred to as Part B may be independently prepared by mixing the required components together in a suitable mixer, e.g., a SpeedMixer. Typically, the part(s) comprising filler have the filler added in a stepwise manner during mixing to ensure it is thoroughly mixed into the composition. Once the Part A and Part B compositions have been made, they may be mixed together in a predetermined weight ratio to form a final silicone elastomeric attachment strip composition, dependent typically on which Part(s) contain filler and the resulting mixture may if deemed necessary be introduced into a suitable container e.g., a sealant cartridge. For structural glazing purposes, the above composition is designed to cure in bulk in under 4 days and have a mode of failure of >90% cohesive failure (CF) and generally has a tensile strength of greater than 0.3 MPa to glass and anodized aluminum when measured in accordance with ASTM D412. It can be pre applied on aluminum profile as a wet applied system and left to cure. Once it is cured, the aluminum profile can be glued directly on glass using a primer onto the glass. The product is developing instant green strength of about 0.1 MPa. Days the product will develop 100% cohesive failure strength with a strength > 0.3 MPa. Once parts A and B have been mixed together into a final silicone elastomeric attachment strip composition, an elastomeric attachment strip can be prepared via either step (D) or (E). Step (D) involves introducing the final silicone elastomeric attachment strip composition into a suitable non-stick mold and curing to form a silicone elastomeric attachment strip; and Step (E) involves applying the final silicone elastomeric attachment strip composition on to a previously primed substrate surface using a non-stick profile to mold a silicone elastomeric attachment strip on the substrate surface and curing said final silicone elastomeric attachment strip composition. Step (D) In the case of step (D), the final silicone elastomeric attachment strip composition is inserted into suitable molds and left to cure. The resulting cured silicone elastomeric attachment strip may then be stored prior to use. The cured silicone elastomeric attachment strips do not adhere to each other but to ensure no unexpected adhesion occurs a release liner may be used on the two opposite sides silicone elastomeric attachment strip which, in use, will be brought into contact with the primed surface of a substrate. The use of a release liner enables such pre-formed strips to be accurately positioned on a pre-primed substrate. As previously discussed, the cured strip does not adhere to the substrate surface directly and does not function as a pressure sensitive adhesive when applied in a cured form on a primed surface. There is a chemical reaction between the primed surface of the substrate and the surface of the strip which is applied thereon. Once the liner is removed from a first surface of the strip, the strip is adhered to a first pre-primed substrate while the release liner on the opposite side of the release liner remains in place until that side of the cured silicone elastomeric attachment strip is positioned and then brought into contact with a second pre-primed substrate. Step (E) In the case of Step (E) the final silicone elastomeric attachment strip composition once prepared is applied wet within a pre-defined, pre-primed region of a first substrate. In step (E) the final silicone elastomeric attachment strip composition surface in contact with the pre-defined, pre-primed region of the first substrate simultaneously undergoes cure of the substrate whilst chemically interacting with the primer and consequently adhering chemically to the substrate surface. Primer As previously indicated, it is a requirement of this disclosure that each substrate to which the aforementioned silicone elastomeric attachment strip is to be attached must be pre-primed, i.e., a suitable primer must be applied onto the substrate surface and be allowed to dry for from 2 to 60 minutes, alternatively from 5 to 15 minutes prior to application of the strip thereon. Any suitable primers may be utilised for this application, they may contain a wide variety of other ingredients, for example one or more silanes with at least three hydrolyzable groups per molecule and catalysts for example titanates, zirconates and / or aluminum organometallic compound as described above. They may additionally include one or more organotin compounds such as but is not limited to, alkyltin ester compounds such as dibutyltin dioctoate, dibutyltin dimaleate, butyltin 2-ethylhexoate dimethyl tin di-neodecyl ester, or dibutyltin dilaurate, dibutyl tin acetate and dibutyl tin 2-ethyl hexanoate, and any combination thereof. Any suitable silicone sealant primer, namely primers used with construction and / or building materials which are used to form the exterior of buildings such as concrete, marble, brick and stone may be used herein but also primers suitable to be used on aluminum and glass surfaces in insulating glazing and curtain wall applications may be used. Commercial primers which may be used may include DOWSIL™ Construction Primer B, DOWSIL™ Construction Primer P, DOWSIL™ 1200 OS Primer and DOWSIL™ Primer-C all of which are commercially available from Dow Silicones Corporation of Midland Michigan USA. If deemed suitable more than one primer may be used to prime the substrate surfaces which the silicone elastomeric attachment strip is / are to adhere to. In one embodiment the primer applied on the substrate surface may be DOWSIL™ 1200 OS Primer. In a further embodiment it was unexpectedly found that when a substrate has a porous surface it is advantageous to treat the substrate surface to which the silicone elastomeric attachment strip is to be applied, first with, for example, DOWSIL™ Construction Primer P which appears to smooth any surface roughness or cracks or the like and then apply a further coat of primer in the form of DOWSIL™ 1200 OS Primer. The primer may be applied on to a substrate using a suitable dispenser such as for example curtain coaters, spray devices die coaters, dip coaters, extrusion coaters, knife coaters and screen coaters which upon cure material provides a coating on said substrate. There is also provided a use of a silicone elastomeric attachment strip produced by the method described above to adhere a primed first substrate to a primed second substrate. There is also provided a curtain wall unit comprising: (a) a frame member, (b) a curtain wall panel, and (c) a silicone elastomeric attachment strip comprising the cured product of a two-part silicone elastomeric attachment strip composition as hereinbefore described, where the silicone elastomeric attachment strip is interposed between the frame member and the curtain wall panel and structurally attaches the curtain wall panel to the frame member. Typically, it is thought that if the thickness of the coating is less than 0.078mm (3 mils), the product will not exhibit sufficient adhesion for structural applications; and if the thickness of the coating is greater than 0.31mm (12 mils), the exposure time for solvent removal may have to be increased. The substrate surfaces between which the structural adhesive strip may be interposed can have any solid form and can comprise any construction material. Examples of suitable forms include decorative articles, devices and mechanical parts in elastomer, foam, flexible, or rigid consistency. Examples of suitable materials include ferrous and nonferrous metals, such as aluminum, copper, gold, iron, platinum, silver, tin, and their alloys and stainless steel; organic polymers such as polyolefins, polyesters, polyamides, polyacrylates, polycarbonates and polyfluoroolefins; primed (e.g., with a silicone adhesion promoter) and unprimed high performance paints such as polyvinylidene fluoride paints, acrylic thermoset paints, polyester powder coat paints, polyurethane paints, and epoxy paints. It may also adhere to cellulosic materials such as paper and wood; textile materials such as cotton and its blends; and siliceous materials such as glass, cement board, concrete, brick, ceramic such as porcelain, china, quartz, and crystal; and natural stones such as granite, marble, and slate. Examples All viscosity measurements were made using a Modular Compact Rheometer (MCR) 302 from Anton Paar GmbH of Graz, Austria using a 25mm diameter rotational plate with a gap of 0.3 mm at a shear rate of 1s-1. All viscosities were measured at 25oC unless otherwise indicated. All mixtures in the Tables are indicated in parts by weight. When vacuum was applied during the process, a vacuum of about 160 mbar (16kPa) was applied. Process for the preparation of component (a) the titanium-based reaction product. Component (a) was prepared for all examples and comparatives, in which it was present, by way of the exact same process. Component (a), the titanium-based reaction product was prepared using a Neulinger 50-liter compounder. 19058 g of dimethylsilanol terminated polydimethylsiloxane having a viscosity of about 750 mPa.s at 25°C was first loaded into the compounder.76.232 g of tetraisopropoxy titanium was then added and the two components were thoroughly mixed in the compounder for 2 minutes at a low speed of between of 5 to 20 rpm using a dissolver disk mixing element to induce high shear. A small amount of gel accumulated on the dissolver disk and was removed using a spatula. Subsequently, the resulting mixture was then mixed for another 2 minutes using a planetary mixing element designed for use in the compounder together with the dissolver disk mixing element. The speed of the planetary mixing element was gradually increased to a maximum of 50 revolutions per minute (rpm) and the speed of the dissolver mixing element was gradually increased to a maximum of 1300 rpm. Once the mixing elements had reached their respective maximum speed, a vacuum was applied and the temperature of the interior of the mixer was raised by shear mixing to about 90ºC. The reaction mixture was continuously mixed under dynamic vacuum for about 90 minutes, after which the reaction was deemed to have been completed and vacuum was released. The resulting component (a) product was allowed to cool back to room temperature and viscosity of the product was measured using a modular compact rheometer type MCR 302 from Anton Paar GmbH of Graz, Austria with a 25mm diameter rational plate having a gap of 0.3mm at a shear rate of 1s- 1. The viscosity of the product was determined to be 23,275 mPa.s at 25°C. Once component (a) had been prepared, Ex.1 to 5 were prepared using the compositions identified in Table 1a. Table 1a: Ex.1 to Ex.5 Part A composition in parts by weight per 100 parts of OH Terminated PDMS (2,000 mPa.s) and Part B composition in parts by weight of trimethoxy terminated PDMS (60,000 mPa.s) Part A Ex.1 Ex.2 Ex.3 Ex.4 Ex.5 1 In the above: Treated fumed silica 1 was AerosilTMR 812 S commercially available from Evonik Operations GmbH. OH terminated PDMS stands for dimethylhydroxy silyl terminated polydimethylsiloxane and trimethoxy terminated PDMS 1 stands for a trimethoxysilyl terminated polydimethylsiloxane which has a viscosity of 60,000 mPa.s at 25oC. Referring to Table 1a and the composition of Ex.1, the following is an example for determining the molar ratio of Si-OH bonds : Si-alkoxy bonds for the combined compositions of Part A and Part Bis provided below: 1) Determining the Si-OH bond content; 2) Determining the Si-alkoxy bond content, and 3) molar ratio of Si-OH bonds : Si-alkoxy bonds. The Mn value provided in this application have been determined by GPC and represent a typical value of the polydiorganosiloxane used. In the present disclosure the number average molecular weight and weight average molecular weight values of component (a) herein may, for example, be determined using a Waters 2695 Separations Module equipped with a vacuum degasser, and a Waters 2414 refractive index detector (Waters Corporation of MA, USA). The analyses were then performed using certified grade toluene flowing at 1.0 mL / min as the eluent. Data collection and analyses may be performed using Waters Empower GPC software. Titanium preparation A was made using a dimethylsilanol terminated polydimethylsiloxane having a viscosity of about 750 mPa.s at 25°C. It is believed that after the preparation there is approximately 100.4 parts by weight or the product per 100 parts by weight of the starting material. Hence the Si-OH bond content of Titanium preparation A was determined as follows. Hence, Molar amount of Si-OH bonds from titanium preparation A per 100g of product = ((Parts of polymer * No of Si-OH bonds) per molecule / Mn) * 100 (Total Number of parts by weight of all ingredients) ((100*2) / 14,800) * 100 = 0.00379 mol per 100g of product (100+100.4+54+100+2) Using the same mathematical equation format, the Si-OH bond content in moles of 2,000 mPa.s Polymer (Mn 22,000) per 100g of product = ((100*2) / 22,000) *100 = 0.00255 mol per 100g of product (100 +100.4+54+100 +2) Total Si-OH bonds = 0.00255 + 0.00379 = 0.00634 moles per 100g of product Similarly in relation to the number of Si – alkoxy bonds in mol of Trimethoxy polymer (60,000 mPa.s, Mn 62,000) per 100g of product = ((100*6) / 62,000) *100 = 0.00272 mol per 100g of product (100+100.4+54+100+2) And Si- alkoxy bond content in mol of 1,6-Bis(trimethoxysilyl)hexane (MW 327) per 100g of product = (((2*6) / 327) *100 = 0.0103 mol per 100g of product (100+100.4+54+100+2) Hence, Total Si – alkoxy bonds = 0.0103+0.00272 = 0.01302 Consequently, the molar ratio of Si-OH bonds : Si-alkoxy bonds = 0.00634 : 0.01302 = 0.49 The ratio was determined in the same way for each example and pertinent comparative but for space saving purposes a single example calculation. In each of the above compositions the Part A and Part B compositions were prepared as follows: Part A Preparation The Part A compositions were made by mixing the Part A ingredients in Table 1 (in parts by weight per 100 parts of the polymer present with a target weight of the products being approximately 100g per composition. The ingredients added were mixed between 5 to 8 times at 3500 rpm for 30 seconds in a DAC 600 FVZ / VAC-P type SpeedMixerTMfrom Hauschild adding the filler step wise until fully incorporated. Part B Preparation The Part B compositions were made by mixing the part B ingredients in Table 1 (in parts by weight per 100 parts of the polymer present with a target weight of the products being approximately 100g per composition. The ingredients added were mixed between 5 to 8 times at 3500 rpm for 30 seconds in a DAC 600 FVZ / VAC-P type SpeedMixerTMfrom Hauschild adding the filler step wise until fully incorporated. Final silicone elastomeric attachment strip composition preparation Subsequently the respective parts A and B were mixed together in a weight Ratio of Part A : Part B corresponding to the parts indicated in the tables again using a DAC 600 FVZ / VAC-P type SpeedMixerTMfrom Hauschild. Once thoroughly mixed the final composition was introduced into a suitable sealant cartridge. Each composition was applied onto aluminum substrate test piece a region of which had been previously primed with a coating of DOWSIL™ 1200 OS Primer. The primer was applied on to a dry-cleaned test piece and left to dry for 5 minutes. Subsequently, samples were applied onto the primed test piece surface using a U-shaped polytetrafluoroethylene (PTFE) profile (mold) and a polymethylmethacrylate (PMMA) sheet lid. No pressure was applied on the sample material and as such the samples were not prepared as pressure adhesives. The PTFE profile / mold was removed after 4 days and the surface of the sample in contact with the PMMA lid was used after 21 days of cure to bond to a primed glass substrate. The glass substrate had the primer firstly applied to glass and left to react for 5 minutes. Then the pre- cured silicone elastomer sample adhered to the aluminum substrate was gently positioned on the primed region of the glass substrate surface and was left to react without any application of pressure for a period of 7 days. After 7 days of contact with the glass, a combined testpiece has an H-shaped cross-section with the strip being the crossbar of the H between the two substrates. The resulting “H shaped test pieces” were then assessed using a Zwick / Roell Proline Materials Testing Machine until rupture of the parts. The results are provided in Table 1b. In one instance the pre-cured silicone elastomer sample was placed on to an unprimed aluminum substrate in the lab with pressure applied and on an unprimed glass substrate of the same type as used in the above examples again with pressure applied and, in each case, the pre-primed elastomer sample did not adhere to the respective substrate despite the pressure applied. Hence, the elastomers produced in accordance with this disclosure do not function as pressure sensitive adhesive once cured. Table 1b: Physical Property results of Ex.1 to Ex.5 Ex.1 Ex.2 Ex.3 Ex.4 Ex.5 SOT (minutes) 55 30 45-60 >70 60-80 The test pieces were prepared in molds having the dimensions of 12 x12 x 50 cm3H-pieces SOT stands for skin over time and is measured in minutes and is the time by when the finger does not have residues left after touching gently the surface of the sealant. The test was conducted at around two minutes intervals until the SOT time was determined. Flow (sag) was determined in accordance with ASTM D2202 for measurement of sealant sagging; Bulk cure was assessed by cutting a silicone elastomer rubber cross bar of an H shaped testpiece to see if any of the composition remained uncured inside the silicone elastomer. % Cohesive failure (CF) was determined visually by observing the surface of the substrate and estimating the percentage of the surface area of on which sealant is left after the substrate and the elastomer have been pulled apart.100% CF means that there is sealant left on 100% of the substrate surface to which the sealant was previously adhered. Tensile strength and Elongation at break were each measured using a Zwick / Roell Proline Materials Testing Machine. The H pieces were assessed at 5.5 mm / min speed until rupture. A series of comparative examples C.1 to C.5 were prepared simultaneously with Ex.1 to 5 using the compositions provided in Table 1c below.

[0002] Table 1c: Comparatives C.1 to C.5 Part A composition in parts by weight per 100 parts of OH Terminated PDMS (2,000 mPa.s) and Part B composition in parts by weight of trimethoxy terminated PDMS (60,000 mPa.s) Part A C.1 C.2 C.3 C.4 C.5 OH Terminated PDMS (2,000 mPa.s) 100 100 100 100 100 1 y , p p silica 1 were the same as above, DMTDN stands for dimethyltin dineodecanoate Each testpiece was assessed in the same way as for Ex.1 to 5 and the results obtained are disclosed in Table 1d below. Table 1d: Physical Property results of C.1 to C.5 C.1 C.2 C.3 C.4 C.5 All test methods were identical to those described above. It can be seen that that both tin (II) (C.1) and tin (IV) (C.2) catalysts can be used to cure the formulation. However, applying the resultant cured elastomer product on a pre-primed glass substrate did not lead to a cohesive failure (0% CF) and furthermore gave a poor lead to very low tensile strength and elongation at break. In C.3 a standard titanium-based catalyst was used but the composition failed to cure. However, in Ex 1 to 5 when using component (a) as polymer / catalyst fully cured elastomers were obtained and were successfully adhered to the pre-primed glass substrate samples. Comparing Ex 1 to 5 to comparative example C.4 and C.5 it can be appreciated that having a molar ratio of Si-OH bonds : Si- alkoxy bonds of from 0.1 and 0.5 is important and lead to 100% cohesive failure was obtained when the product was adhered to a pre-primed glass substrate. This shows that these formulations -containing the 1 to 5 parts of hexamethoxydisilyl hexane can be used to produce strips that can be used for structural strips to bond glass to aluminum. C4 and C5 are comparative examples outside of the working range either not enough 1,6-Bis(trimethoxysilyl)hexane (HMSH) to be within the required molar ratio of Si-OH bonds : Si-alkoxy bonds (C.4, 1pph, Si – OH : Si - alkoxy molar ratio = 0.75 : 1) or too much HMSH (C.5, 20pph, molar ratio of Si-OH bonds : Si-alkoxy bonds = 0.06 : 1) so as to be too high to be inside the required ratio. A further series of examples Ex.6 to 8 and comparatives C. to C.8 were prepared with the compositions depicted in Table 2a below. Again, the compositions are provided in parts by weight per 100 parts by weight of OH Terminated PDMS (2,000 mPa.s) and Part B compositions in parts by weight per 100 parts by weight of the respective Trimethoxy terminated PDMS therein. Table 2a: Compositions of Ex.6 – Ex.8 and C.6 to C.8 with Part A compositions in parts by weight per 100 parts by weight of OH Terminated PDMS (2,000 mPa.s) and Part B compositions in parts by weight per 100 parts by weight of the respective Trimethoxy terminated PDMS therein. Part A Ex.6 Ex.7 Ex.8 C.6 C.7 C.8 i 4 1 In the above all components were as above other than the following trimethoxy terminated PDMS 2 was the same as Trimethoxy terminated PDMS 1 except for having a viscosity of 357 mPa.s; trimethoxy terminated PDMS 3 was the same as Trimethoxy terminated PDMS 1 except for having a viscosity of 2000 mPa.s; The untreated fumed silica was CAB-O-SILTMLM-150 sold commercially by the Cabot Corporation. The precipitated calcium carbonate 1 used was SocalTM312 sold commercially by Imerys S.A. The exact same tests as undertaken in Tables 1b and 1d above were undertaken on these samples and the results are provided in Table 2b below. Table 2b: Physical Property results for Ex.6 to 8 and C.6 to 8 Ex.6 Ex.7 Ex.8 C.6 C.7 C.8 SOT (min) >70 50 45-70 20 18 60-105 . . or use with precipitated calcium carbonate as filler instead of treated silica and that smaller trimethoxy terminated PDMS cross- linkers can be used leading to acceptable values of tensile strength and elongation. C.6 to C.9 in comparison show that using a standard silane cross-linker such as methyltrimethoxy silane does not generate acceptable adhesion. Similarly using untreated silica does not provide a suitable structural strip. Ex.9 and Ex.10 were also prepared in accordance with the compositions depicted in Table 3a below. In these instances, both Parts A and B contained filler.

[0003] Table 3a Compositions of Ex.9 and 10 with Part A compositions in parts by weight per 100 parts by weight of OH Terminated PDMS (2,000 mPa.s) and Part B compositions in parts by weight per 100 parts by weight of Trimethoxy terminated PDMS (60,000 mPa.s). Ex.9 Ex.10 Part A The Ex.9 Part A composition was produced in a 5-liter Neulinger mixer.1865 g of component (a) and 1858 g of the OH Terminated PDMS (viscosity 23°C 2,000 mPa.s) was added in the mixer, then 777 g of EvonikTMAerosil R 812S (hydrophobically treated fumed silica) was added in four additions and the mixture was further mixed for 3 minutes between each addition, in each case under vacuum. After the last addition the product was mixed for 3 minutes without vacuum and then 5 minutes under vacuum and then packaged in 310 ml cartridges. Preparation of Ex.9 Part B composition The Ex.9 Part B composition was produced in a Drais Mixer. 2667g of trimethoxy terminated PDMS (viscosity 23°C ca.60,000 mPa.s) and 66.6 g of 1,6-Bis(trimethoxysilyl)hexane was added in the mixer. Then 267g of Evonik Aerosil R 812S treated fumed silica was added in three additions and mixed for 2 minutes between each addition. After the last addition the resulting mixture was mixed for 2 minutes without vacuum and subsequently for 5 minutes under vacuum after which the final product was packaged in 310 ml cartridges. Preparation of Ex.10 Part B composition The Ex.9 Part B was produced in a Drais Mixer. 2575g of trimethoxy terminated PDMS (viscosity 23°C ca.60,000 mPa.s) and 167 g of 1,6-Bis(trimethoxysilyl)hexane was added in the mixer. Then 258g of Evonik Aerosil R 812s treated fumed silica was added in three additions and mixed for 2 minutes between each addition. After the last addition the resulting mixture was mixed for 2 minutes without vacuum and then 5 minutes under vacuum and then packaged in 310 ml cartridges. Preparation of Ex.9 and Ex.10 Samples The resulting Part A and respective part B compositions of Ex.9 and Ex.10 were mixed together in a respective Part A : Part B weight ratio of 2.1 : 1 using a DAC 600 FVZ / VAC-P type SpeedMixerTMfrom Hauschild. After mixing for 2 times 30 seconds at 2300 rpm the resulting final mixture was introduced into a sealant cartridge and subsequently using the cartridge in a sealant gun the composition was introduced between a primed aluminum substrate and a sheet of polymethylmethacrylate (PMMA) lid in a U-shaped profile made from polytetrafluoroethylene (PTFE). The PTFE profile was removed after 4 days and the consequently pre-cured surface in contact with PMMA was used after 21 days of cure to bond to a pre-primed glass substrate. The primer, DOWSIL™ 1200 OS Primer commercially available from Dow Silicones Corporation, was firstly applied to the glass substrate and left to react for 5 minutes. Then the pre-cured silicone elastomer (previously adhered to the pre-primed aluminum is applied gently on the primed glass and left to react without pressure. After 7 days of contact with the glass, the resulting H pieces are submitted to ageing and / or testing. Flow and bulk cure tests were conducted in the same manner as above together with green strength testing. The results are provided in Table 3b below. Table 3b: Physical property results of Ex.9 and Ex.10 Ex.9 Ex.10 Flow N N Green strength and Modulus measurements were all taken using the aforementioned Zwick / Roell Proline Materials Testing Machine described above based on 10 specimen, from which the average is shown in Table 3b above. It can be seen that mechanical properties of these formulations are excellent. In our view the examples herein provide confirmation that compositions and elastomers as described herein in accordance with the disclosure are suitable to pass the structural glazing requirements such as ETAG 002. A further series of comparative examples C.7 to C.10 using the component (a) as polymer and catalyst but otherwise having distinctly different compositions were prepared for comparison. The compositions are provided in Table 4a below. Table 4a Compositions of C.7 to C.10 Part A compositions in parts by weight per 100 parts by weight of component (a) and Part B compositions in parts by weight per 100 parts by weight of Trimethoxy terminated PDMS (2,000 mPa.s). C.7 C.8 C.9 C.10 Part A dimethyldichlorosilane which is commercially available under the trade name AEROSILTMR 974 by from Evonik Operations GmbH. The precipitated calcium carbonate 2 was commercially available under the Trade name WinnofilTMSPM from Imerys S.A. Table 4b: Physical Property results of C.7 to C.10 C.7 C.8 C.9 C.10 It can be seen that compositions C.7 to C.10 mainly had very fast SOT values but poor % cohesive and especially poor tensile Strength and elongation at break results and consequently are not suited for strips as described herein.

Claims

CLAIMS 1. A two-part silicone elastomeric attachment strip composition wherein: a first part composition comprises the following components: (a) a titanium-based reaction product obtained or obtainable from a process comprising the steps of: (i) mixing a first ingredient, an alkoxy titanium compound having from 2 to 4 alkoxy groups with a second ingredient, a linear or branched polydiorganosiloxane polymer having at least two terminal silanol groups per molecule; (ii) enabling the first and second ingredients to react together by stirring under vacuum to form a reaction product; and (iii) collecting the reaction product of step (ii); (b) at least one linear or branched polydiorganosiloxane polymer(s) having at least two terminal silanol groups per molecule; and a second part of the composition comprises the following components: (a’) at least one trimethoxy terminated polysiloxane(s) (b’) a bis(trialkoxysilyl)alkane having from 8 to 20 carbons per molecule, a trialkoxyphenylsilane having from 8 to 20 carbons per molecule; or a mixture thereof; and a component (c) which is mixed into the first part composition, the second part composition or both the first part composition and the second part composition; wherein: (c) is at least one filler, comprising fumed silica, precipitated silica, precipitated calcium carbonate or a mixture thereof, which filler is optionally hydrophobically treated; which composition has a molar ratio of Si-OH bonds : Si-alkoxy bonds of from 0.1 : 1 to 0.5 :

1.

2. A two-part silicone elastomeric attachment strip composition in accordance with claim 1 wherein the alkoxy group of component b’ has from 1 to 4 carbons per alkoxy group, for example, methoxy, ethoxy, propoxy, n-butoxy and t-butoxy groups; and the alkane group may have from 2 to 10 carbons and is linear or branched.

3. A two-part silicone elastomeric attachment strip composition in accordance with claim 1 or 2 wherein component b’ comprises one or more of 1,6-bis (trimethoxysilyl)hexane 1,5-bis (trimethoxysilyl)pentane and 1,7-bis (trimethoxysilyl)heptane.

4. A two-part silicone elastomeric attachment strip composition in accordance with any preceding claim which additionally comprises one or more additives selected from adhesion promoters, non-reinforcing fillers, rheological additives, plasticizers and / or extenders, pigments & colorants, UV absorbers, antioxidants, UV and / or light stabilizers and biocides.

5. A structural attachment strip which is the cured product of any preceding claim.

6. A structural attachment strip in accordance with claim 5 which is not sticky to the touch after cure.

7. A method of preparing a silicone elastomeric attachment strip comprising the steps of (A) preparing a first part composition by mixing components (a) and (b) where:(a) is a titanium-based reaction product obtained or obtainable from a process comprising the steps of: (i) mixing a first ingredient, an alkoxy titanium compound having from 2 to 4 alkoxy groups with a second ingredient, a linear or branched polydiorganosiloxane polymer having at least two terminal silanol groups per molecule; (ii) enabling the first and second ingredients to react together by stirring under vacuum to form a reaction product; and (iii) collecting the reaction product of step (ii); (b) at least one linear or branched polydiorganosiloxane polymer having at least two terminal silanol groups per molecule; (B) separately preparing a second part composition by mixing components (a’) and (b’) where: (a’) is at least one trimethoxy terminated polysiloxane; and (b’) is a bis(trialkoxysilyl)alkane having from 8 to 20 carbons per molecule, a trialkoxyphenylsilane having from 8 to 20 carbons per molecule; or a mixture thereof; and a component (c) which is mixed into the first part composition, the second part composition or both the first part composition and the second part composition; wherein: (c) is at least one filler, comprising fumed silica, precipitated silica, precipitated calcium carbonate or a mixture thereof, which filler is optionally hydrophobically treated; (C) Mixing the first part composition and the second part composition together in a suitable weight ratio to form a final silicone elastomeric attachment strip composition such that the final silicone elastomeric attachment strip composition has a molar ratio of Si-OH bonds : Si-alkoxy bonds of from 0.1 : 1 to 0.5 : 1; and either (D) or (E), wherein: (D) is introducing the final silicone elastomeric attachment strip composition into a suitable non-stick mold and curing to form a silicone elastomeric attachment strip; or (E) is applying the final silicone elastomeric attachment strip composition on to a previously primed substrate surface using a non-stick profile to mold a silicone elastomeric attachment strip on the substrate surface and curing said final silicone elastomeric attachment strip composition.

8. A silicone elastomeric attachment strip made in accordance with the above method.

9. A silicone elastomeric attachment strip in accordance with claim 5 or 8 which is not a pressure sensitive adhesive and is adhered to a substrate surface by way of a chemical interaction between the silicone elastomeric attachment strip and pre-applied primers on the substrate surface.

10. Use of a silicone elastomeric attachment strip produced by the method of claim 2 to adhere a primed first substrate to a primed second substrate or to adhere a first substrate on to which the silicone elastomeric attachment strip produce was pre-applied to an optionally primed second substrate.

11. A curtain wall unit comprising: (I) a frame member,(II) a curtain wall panel, and (III) a silicone elastomeric attachment strip in accordance with claim 5 or 8 where the silicone elastomeric attachment strip is interposed between the frame member (I) and the curtain wall panel (II) and structurally attaches the curtain wall panel (II) to the frame member (I).

12. A curtain wall unit in accordance with claim 11 wherein the frame member (I) and curtain wall panel (II) are each treated with a primer prior to adherence to the silicone elastomeric attachment strip in accordance with claim 5 or 8.

13. Use of a silicone elastomeric attachment strip in accordance with claim 5 or 8 in a curtain wall unit comprising: (I) a frame member, (II) a curtain wall panel, and (III) a silicone elastomeric attachment strip in accordance with claim 5 or 8 where the silicone elastomeric attachment strip is interposed between the frame member (I) and the curtain wall panel (II) and structurally attaches the curtain wall panel (II) to the frame member (I).

Images